Materials




                                                                                                        Greenstonebreccia                                                                                                            "Black Beauty"

Specific gravity: 3,30 kg/m3
Water absorption: 0,07 weight


                                                        

Conglomerate 
"Picasso"


Specific gravity: 2,85 kg/m3




Greenstone
   "Mon Amour"
  

 



Red Conglomerate
"Moonlight Red" 

 

 

 

 

 

 

 

 

 

 

 

 



BLACK BEAUTY’S QUALITIES

We know that today’s quality-conscious consumer will not buy a product based on appearance alone. This is one of the reasons why we commissioned the rock engineering department of the Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology (SINTEF Bergteknikk) to test Black Beauty for us. The results of the test are very good. Details of the test report are given below.

The sedimentary rock popularly known as Black Beauty or Landøy Stone is found at the boundary between greenstone and conglomerate. When polished, the surface acquires a dark colour, mottled with light green and red, as well as other nuances.

According to the test result, the stone has very low water absorption ratio, which is an excellent property for both indoor and outdoor use.

In terms of strength and durability the stone is comparable with granite. Proof, therefore, that a beautiful and delicate appearance does not always mean poor quality. Black Beauty can withstand rough treatment day after day, year after year.


- Who said that beauty wasn’t everlasting?!

 

  • When polished, the stone acquires a lovely gentle radiance, giving it an exclusive quality
     
  • Black Beauty is a natural mosaic. This makes it totally unique and alive. You never get bored with it. Take a close look at the polished surface and you get the impression of being in a river bed with eddies and ripples.
     
  • Landøy stone - Black Beauty complements all types of wood. It also goes well with other types of stone, ceramic tiles and slate.


The stone’s fascinating history
by Ebbe Hartz (D. Geol)

Black Beauty is a fascinating and heterogeneous composition of rock types, colours and shapes - a so-called conglomerate. It has taken a hundred million years to form, and its history spans the most dramatic period in Norway’s geological development.

How was the stone formed?

The dark green and red components in the stone are volcanic rocks that were formed in an oceanic region west of Norway more than 425 million years ago. This ocean is called the proto-Atlantic.

Four hundred million years ago, the continental drift resulted in the formation of what was the world’s largest mountain range. As West Norway collided with Greenland, the ancient ocean floor was forced upwards and the Caledonian mountain range was formed. In scale it could be compared with the Himalayas today.

Then, around 380 million years ago, the mountains were subjected to erosive forces. Coarse materials such as sand and gravel were deposited by river systems in the valleys. This is the black rock we see in Black Beauty, i.e. the ancient sea bed, surrounded by light sand.

During this erosion process the conglomerate was simultaneously heated up to a couple of hundred degrees. The sand and pebbles that were deposited in the river beds were thus formed into stone. In fact, it was this heating process that gave Black Beauty its characteristic hardness.

We hope you get a lot of pleasure from using Black Beauty in your home - it’s a stone with both soul and history!

Ebbe Hartz

DETAILS FROM THE SINTEF REPORT
By Lisbeth Alnæs, research fellow.

Natural stone from Værlandet

General


Værlandet, Melvær, Bulandet and Sandøy are the outermost islands situated in the mouth of the fjord west of Askvoll in the county of Sogn og Fjordane. This small collection of islands and holms provide an interesting journey through Norwegian geological history. In the north you find sedimentary rocks such as conglomerate, sandstone and breccia in close proximity with greenstone. Several discoveries of fossilised plants have been made on Bulandet and Værlandet.

Greenstone is the oldest rock type on Værlandet, deposited as lava on the ocean floor during a period that spans from 570 to 430 million year ago (Cambro-Silurian Period).

The sedimentary rocks were deposited on land around 400-345 million years ago in a basin that sank along major fracture zones running in an east-west direction. These fracture zones were caused by tremendous forces in the earth’s crust, and huge amounts of rounded clasts of previously formed rocks, together with sand and gravel, were transported by rivers that ran from the north of the basin. These sediments have a total thickness of 3,500 metres. Sedimentary breccia is the oldest of the sedimentary rocks and forms a transition zone between greenstone and the overlying conglomerate. Sandstone, which features on holms south of Værlandet, represents the youngest element of the loose material deposited in this basin.



Sedimentary breccia


The greenstone breccia on Værlandet lies between greenstone and conglomerate and as mentioned forms a transition zone between the two. Breccia appear as massive ridges in the terrain and to a certain extent is fissured. The rock comprises angled fragments of green to almost black greenstone that have been torn loose from the underlying greenstone. The fragments can also be deep red in colour due to the presence of jasper. The size varies from 0.5-10 cm, usually around 4-5 cm, and they are cemented together by brownish-grey sandstone. The greenstone fragments may also contain thin, bright traces consisting of epidote and calcareous spar. The stone polishes well and results in a dark-brown to black surface. It is possible to quarry large blocks of the stone.

Greenstone

As mentioned, the greenstone was originally deposited as lava, which later transformed into a dense, fine-grained rock that primarily consisted of amphibole, epidote, feldspar, titanite and some calcareous spar. Immediately under the breccia are greenstone deposits that have been broken up and later cemented together by veins and thin traces of bright minerals - feldspar, epidote, carbonate and quartz. When polished these acquire a greenish-yellow to grey-white hue. These run through the greenstone in several directions and give the stone a lively pattern against a dark green to black background. The greenstone also contains rich deposits of jasper. The red jasper generally forms an outer zone around the greenstone deposits and gives the rock nuances of reddish-brownish “clouds”. It should be possible to quarry small blocks and smaller pieces of this greenstone variant near to the breccia.

Summation

The following average values are obtained for breccia:

Bulk density: 3002 kg/m3
Open porosity: 0.2%
Water absorption. 0.07% by weight
Bending tensile strength: 22.7 N/mm2
Compressive strength: 191.5 N/mm2
Abrasion index: 2.3 and above

Mineral content in the greenstone fragments:

45% chlorite
35% amphibole
10% feldspar
3% muscovite
2% hematite
2% epidote

Mineral content in the intermediary deposit:

45% quartz and feldspar
14% chlorite
15% carbonate
10% epidote
10% amphibole
3% hematite
2% muscovite
<1% biotite, titanite, zircon

Lisbeth Alnæs.